Stabilization of phosphosulfurized hydrocarbons



2,804,43l Patented Aug. 27, 1957 tic STABHJZATION OF PHOSPHOSULFURIZED HYDROCARBON S Stephen L. Wythe, Plainfield, N. 1., assignor to Ease Research and Engineering Company, a corporation of Delaware No Drawing. Application April 18, 1055, Serial No. 502,240

13 Claims. (Cl. 25246.6)

This invention relates to the odor stabilization of phosphosulfurized hydrocarbons. More particularly, the invention relates to an improved method for odor stabilizing phosphosulfurized hydrocarbons, to the stabilized products themselves, and to oil compositions containing the stabilized products as useful additives.

Many organic sulfur-containing compounds normally evolve hydrogen sulfide during storage, transportation, or use. Because of the obnoxious odor of hydrogen sulfide, this evolution is quite objectionable. Frequently, it is desired to use. such compounds as additives for mineral oil or synthetic oil compositions, such as lubricating oils, to impart to the compositions various desired properties, such as extreme pressure properties, anti-corrosive or anti-oxidant properties, detergent properties, and the like. However, compositions containing even small amounts of unstable sulfur-containing compounds will evolve hydrogen sulfide. Users of such compositions object to these odors and consequently the salability of the product is impaired. Many organic compounds that have been sulfurized by treatment with sulfur, sulfides of phosphorus and the like show this characteristic instability with respect to hydrogen sulfide evolution. Phosphosulfurized hydrocarbons have been particularly difficult to odor stabilize. V

Numerous attempts have been made in the prior art to stabilize such sulfur-containing compounds or compositions containing these compounds. In some cases, inhibitors have been added which tend to minimize H2S evolution. Neutralization of acidic sulfur-containing materials with basic reagents has also been employed but this method frequently fails to give a stable product. Another procedure that has widespreadusag'e involves blowing the material with air or other gaseous materials in order to stabilize'the material against H25 evolution. One of the most effective methods of the prior art for reducing hydrogen sulfide evolution from sulfur-containing compounds has been accomplished by reacting these compounds with an organic compound containing at least one reactive olefinic double bond.

it has now been found that phosphosulfurized hydrocarbons can be effectively stabilized with respect to hydrogen sulfide evolution by reacting them with a combination of an organic peroxide and a cyclic terpene. The method of this invention is more effective in stabilizing phosphosulfurized hydrocarbons than those methods of the prior art.

The present invention is especially directed to those phosphosulfurized hydrocarbons which are outstanding lubricating oil additives, such as phosphosulfurized polybutenes and bright stocks, although it will be clearly understood that the method of this invention is appli cable to other phosphosulfurized hydrocarbons which normally evolve hydrogen sulfide. Examples of hydrocarbons which may be phosphosulfurizcd and stabilized by the method of this invention include bright stock residuums, lubricating oil distillates, petrolatur'ns, paralfin waxes, etc.; olefins, such as isobutylene, amylene,'decene,

dodecene, cetene, octadecene, etc.; olefin polymers having molecular weight ranges from to 50,000, such as those of ethylene, propylene, butylene, isobutylene, amylenes, etc.; diolefins, such as butadiene, isoprene, chloroprene, cyclopentadiene, etc.; acetylenes; copolymers of low molecular weight monoolefins and diolefins having molecular weight ranges of about 1,000 to 30,000; aro matics, such as benzene, naphthalene, anthracene, toluene, xylene, diphenyl, etc.; alkyl aromatics; cyclic aliphatics; petroleum fractious; condensation products of halogenated aliphatic hydrocarbons with aromatic compounds and the like.

The phosphosulfurized hydrocarbons of this invention can be prepared by methods well known to the art by the reaction of phosphorus sulfides with hydrocarbons at elevated temperatures. The sulfides of phosphorus which can be employed include P283, P285, P453, P487, or other phosphorus sulfides and is preferably phosphorus pentasnlfide (P285). Mixtures of two or more phosphorus sulfides may also be employed as Well as mixtures of elemental phosphorus and sulfur. The phosphosulfurization reaction is conveniently carried out at an elevated temperature of about 200 to 600 F, preferably about 300 to about 550 F., using about 1 to about 5 molecular proportions of the hydrocarbon to 1 molecular proportion of the phosphorus sulfide in the reaction. The reaction will generally be carried out until the maximum amount of sulfur or phosphorus sulfide has been added to the hydrocarbon althoughthis is not essential. The reaction time is not critical and the time required to cause the maximum amount of phosphorus sulfide to react will vary with the temperature. A reaction time of 2 to 10 hours is frequently necessary and, if desired, the reaction product may be further treated by blowing with steam, alcohol, ammonia, or an amine at an ele vated temperature of about 200 F. to improve the odor thereof to a certain extent. 7

Particularly preferred hydrocarbons which are phosphosulfurized include mineral oil bright stocks and polybutenes. The bright stock may be reacted with about 5 to 25%, preferably 10 to 20%, by weight of P285 (based on the bright stock). I

The polybutene employed is preferably polyisobutylene. Generally the polybutenes will have a molecular weight in the range of about 500 to 25,000, preferably about 800 to 2,000. Particularly useful polybutenes are polyisobutylenes of about 1000 to 1500 molecular weight which have been reacted with about 10 to 15% by weight of P285 (based on the polyiso'outylene).

The cyclic terpenes employed in the stabilization reaction have the formula CIOHIG. These particular terpenes are a well-known class of chemical compounds which include (1) bicycli'c terpenes, e. g. a pinene, B pinene, carene, camphene, bornylene, afenchene, e fenchene, etc. (the preferred 'bicyclic terpene is a pinene) and (2) monocyclic terpenes, e. g. dipentene, terpinolene, etc. Commercial dipentene may be employed which contains about 31% dipentene, 39%. terpinolene, 6% a pinene, 10% para-cymene, 7% a terpeneol, 5% A 2,4(8)-p-methodiene, and 2% residue.

The organic peroxides employed in this invention have the formula ROOX where R is an acyl or hydrocarbonradical, preferably containing about 2 to 10 carbon atoms, and Xis selected from the group consisting of hydrogen atoms (hydroperoxides) and R radicals. These organic peroxides are a well-known class of chemical compounds. Preferably R is an alkyl radical'containing about'2 to 10 carbon" atoms and X is hydrogen. -Specific examples of these organic peroxides (including hydroperoxides) include t-butyl hydroperoxide, t-butyl peroxide, benzoyl peroxide, lauroyl peroxide, t-butyl perbenzoate, methyl ethyl ketone peroxide and the like. Tert. butyl hydroperoxide is particularly preferred.

In accordance with the present invention, the phosphosulfurized hydrocarbon is reacted with the combination of the cyclic terpene and a small, but catalytic acting amount of the organic peroxide. The reaction may be carried out at a temperature in the range of about 100 to 400 F. and preferably is carried out at a temperature in the range of about 250 to 350 F. The reaction will generally be carried out for a period of time in the range of about 0.5 to 10 hours, preferably for about 2 to 4 hours. However, it will be understood that the particular reaction time employed will depend to a certain extent upon such factors as the degree of stabiliz'ation desired and the temperature employed.

Generally about 1% to 200% and preferably about 25% to 125% by weight of the cyclic terpene will be employed based on the amount of the phosphosulfurized hydrocarbon present. These relatively large amounts of cyclic terpene are preferred so as to assume effective stabilization, although only a small amount of the terpene is consumed in the reaction. The amount of the organic peroxide employed should be suflicient to catalyze the reaction between the phosphosulfurized hydrocarbon and the cyclic terpene. Generally the amount of the organic peroxide employed will be about 0.001 to 0.5 mole, preferably 0.01 to 0.2 mole, per mole of the phosphosulfurized hydrocarbon.

The reaction may be carried out, if desired, with the reactants dissolved in an inert solvent or diluent, such as a mineral lubricating oil in the case where the final product is to be employed as a lubricating oil additive. It is preferred to separate unreacted terpene and the peroxide decomposition products by distillation from the stabilized phosphosulfurized hydrocarbon after the reaction is completed.

The following example is intended to set forth the invention in greater detail but it will be understood that it is not intended that the invention be limited by this example in any way.

EXAMPLE A. Preparaton of P285 treated polyisobutylene 100 grams of P285 were added to 1,000 grams of a polyisobutylene (molecular weight=1,100) in a 5-liter three-necked flask, and the mixture heated to 425 F. and held there for eight hours with stirring in an atmosphere of nitrogen. At the end of this period, the mixture was cooled to 350 F., and 1,100 grams of a solvent extracted and dewaxed mineral lubricating oil distillate having an S. S. U. viscosity at 210 F. of about 45 were added. The solution was filtered through a heated Biichner funnel using Hi-Flo filter aid. The product so obtained will be designated as Product A.

A blend containing 4 wt. percent of Product A in a mineral lubricating oil base stock was then prepared. 800 cc. of this blend were placed in a 1-liter bottle and heated for one hour at 130 F. A strip of paper saturated with a solution of lead acetate was held over the mouth of the bottle for five minutes, and then examined for the intensity of the lead sulfide stain. The bottle was then heated for an additional three hours and rerated. The stains were rated on a scale: 0=no stain; =heavy stain with a trace of silvery overlay; 10+=heavy stain with considerable silvery overlay. The results were as follows:

4 B. Treatment of Product A with a-pinene 500 grams of Product A and 500 grams of freshly distilled a-pinene were heated with stirring at 350 F. for three hours. Unreacted ot-pinene was stripped from the reaction mixture by distillation under reduced pressure (13-17 mm. Hg) at 300 F. A total of 491 grams of material were recovered from the still pot as residue. A 4 wt. percent blend of this product in the mineral lubricating oil base stock of Part A was rated as above for B28 odor. The results were as follows:

1 Hour 4 Hours Hts Rating 9 10 C. Treatment of Product A with t-butyl hydroperoxide 10 grams of t-butyl hydroperoxide were added to 500 grams of Product A, and the mixture heated with s t irring for three hours at 320 F. Unreacted material and peroxide decomposition products were removed by distillation under reduced pressure (13-17 mm. Hg). 492 grams of material were recovered from the still pot as residue. I

A 4 wt. percent blend of this product in the mineral lubricating oil base stock of Part A was rated for HzS stability as described above. The results were as follows:

1 Hour 4 Hours HzS Rating 8 10 D. Treatment of Product A with t-butyl hydroperoxide and a-pinene 1 Hour 4 Hours HtS Rating 3 4 It will be noted that a slight improvement in H2S evolution was obtained by treating the P285 treated polyisobutylene with either a-pinene or tert.-butyl hydroperoxide individually. However, it will be noted that a substantial reduction in HzS evolution, as compared to these individual treatments, was realized when the P255 treated polyisobutylene was reacted with ot-pinene and a small amount of tert.-butyl hydroperoxide. The advantage of the present invention can be realized either as reduced hydrogen sulfide evolution for a given set of treating conditions or as a more effective and more rapid treating procedure for a given degree of reduction in H23 evolution.

When the products of the present invention are employed in lubricating oils, they are preferably added in proportions of about 0.001 to about 10.0% and preferably 1.0 to about 6.0%. The proportions giving the best results will vary somewhat according to the nature of the additive and the specific purpose which the lubricant is to serve in a given case. For commercial purposes, it is convenient to prepare concentrated oil solutions in which the amount of additive in the composition ranges from 25% to 75% by weight, and to transport and store them in such form. In preparing 'a lubricating oil composition for use as a crankcase lubricant, the additive concentrate is merely blended with the base oil in the required amount.

The products of the present invention may be employed not only in ordinary hydrocarbon lubricating oils but also in the heavy duty type of lubricating oils which have been compounded with such detergent type additives as metal soaps, metal petroleum sulfonates, metal phenates, metal alcoholates, metal alkyl phenol sulfides, metal organo phosphates, phosphites, thiophosphates, and thiophosphites, metal xanthates and thioxanthates, metal thiocarbamates, and the like. Other types of additives, such as phenols and phenol sulfides, may also be present.

The lubricating oil base stock used in the compositions of this invention may be straight mineral lubricating oils or distillates derived from paraffinic, naphthenic, asphaltic or mixed base crudes, or, if desired, various blended oils may be employed as well as residuals, particularly those from which asphaltic constituents have been carefully removed. The oils may be refined by conventional methods using acid, alkali and/ or clay or other agents such as aluminum chloride, or they may be extracted oils produced by solvent extraction with solvents such as phenol, sulfur dioxide, etc. Hydrogenated oils or white oils may be employed as well as synthetic oils prepared, for example, by the polymerization of olefins or by the reaction of oxides of carbon with hydrogen or by the hydrogenation of coal or its products. In certain instances cracking coal tar fractions and coal tar or shale oil distillates may also be used.

Synthetic lubricating oils having a viscosity of at least 30 S. S. U. at 100 F. may also be employed, such as esters of monobasic acids (e. g. ester of Ca Oxo alcohol with Ca Oxo acid; ester of C13 Oxo alcohol with octanoic acid, etc.), esters of dibasic acids (e. g. di-Z-ethyl hexyl sebacate; di-nonyl adipate, etc.), esters of glycols (e. g. C12 Oxo acid diester of tetraethylene glycol, etc.), complex esters (e. g. the complex ester formed by reacting one mole of sebacic acid with two moles of tetraethylene glycol and two moles of 2-ethyl-hexanoic acid; the complex ester formed by reacting one mole of tetraethylene glycol with two moles of sebacic acid and two moles of 2-ethyl hexanol; the complex ester formed by reacting together one mole of azelaic acid, one mole of tetraethylene glycol, one mole of Ca Oxo alcohol, and one mole of Ca Oxo acid), esters of phosphoric acid (e. g. the ester formed by contacting three moles of the mono methyl ether of ethylene glycol with one mole of phosphorus oxychloride, etc.), halocarbon oils (e. g. the polymer of chlorotrifiuoroethylene containing twelve recurring units of chlorotrifluoroethylene), alkyl silicates (e. g. methyl polysiloxanes, ethyl polysiloxanes, methyl-phenyl polysiloxanes, ethyl-phenyl polysiloxanes, etc.), sulfite esters (e. g. ester formed by reacting one mole of sulfur oxychloride with two moles of the methyl ether of ethylene glycol, etc.), carbonates (e. g. the carbonate formed by reacting Ca Oxo alcohol with ethyl carbonate to form a half ester and reacting this half ester with tetraethylene glycol), mercaptals (e. g. the mercaptal formed by reacting 2-ethyl hexyl mercaptan with formaldehyde), formals (e. g. the formal formed by reacting C13 Oxo alcohol with formaldehyde), polyglycol type synthetic oils (e. g. the compound formed by condensing butyl alcohol with fourteen units of propylene oxide, etc.), or mixtures of any of the above in any proportions. Also mixtures or blends of these synthetic lubricating oils with the aforementioned mineral oils may be employed. In addition, for special applications, animal, vegetable or fish oils or their hydrogenated or voltolized products may be employed in admixtures with the aforementioned mineral oils and/or synthetic oils.

For the best results the base stock chosen should normally be an oil which with the new additive present gives the optimum performance in the service contemplated. However, since one advantage of the additives is that their use also makes feasible the employment of less satisfactory mineral oils, no strict rule can be laid down for the choice of the base stock. The additives are normally suificiently soluble in the base stock, but in some cases auxiliary solvent agents may be used. The lubricating oils will usually range from about 35 to 200 seconds Saybolt viscosity at 210 F. The viscosity index may range from 0 to or even higher.

Other agents than those which have been mentioned may be present in the oil composition, such as dyes, pour point depressants, heat thickened fatty oils, sulfurized fatty oils, sludge dispersers, anti-oxidants, e. g. phenyl or naphthylamine, thickeners, viscosity index improvers, e. g. polyisobutylene; oiliness agents, resins, rubber, ole-' fin polymers, and the like. 1

Assisting agents which are particularly desirable as plasticizers and defoamers are the higher alcohols having preferably 8 to 20 carbon atoms, e. g. octyl alcohol, lauryl alcohol, stearyl alcohol, and the like.

In addition to being employed in lubricants, the additives of the present invention may also be used in other mineral oil and synthetic oil products such as motor fuels, hydraulic fluids, torque converter fluids, cutting oils, flushing oils, turbine oils, transformer oils, industrial oils, process oils, and the like, and generally as useful additives in mineral oil and synthetic oil products. They may also be used in gear lubricant-s, greases and other products containing mineral oils or synthetic oils as ingredients.

What is claimed is:

1. An improved method for reducing the evolution of hydrogen sulfide from phosphosulfurized hydrocarbons which comprises treating a phosphosulfurized hydrocarbon with about 1% to 200% by weight, based on the phosphosulfurized hydrocarbon, of cyclic terpene in the presence of about 0.001 to 0.5 mole, per mole of phos phosulfurized hydrocarbon, of organic peroxide having the formula ROOX where R is a radical selected from the group consisting of acyl radicals and hydrocarbon radicals containing 2 to 10 carbon atomsand X is selected from the group consisting of R radicals and hydrogen atoms, said treatment being carried out at a temperature of about 100 to 400 F. for about 0.5 to 10 hours.

2. An odor stabilized phosphosulfurized hydrocarbon product prepared by the method of claim 1.

3. A lubricating oil composition comprising a major proportion of a mineral lubricating oil and about 1.0 to 6.0% by weight, based on the total composition, of an odor stabilized phosphosulfurized product prepared by the method of claim 1.

4. An additive concentrate consisting essentially of a mineral lubricating oil and about 25% to 75% by weight of an odor stabilized phosphosulfurized hydrocarbon product prepared by the method of claim 1.

5. An improved method for reducing the evolution of hydrogen sulfide from phosphosulfurized hydrocarbons which comprises treating a phosphosulfurized hydrocarbon with about 25% to by weight, based on the phosphosulfurized hydrocarbon, of cyclic terpene in the presence of about 0.01 to 0.2 mole, per mole of phosphosulfurized hydrocarbon, of organic peroxide of the formula ROOH where R is an alkyl radical containing 2 to 10 carbon atoms, said treatment being carried out at a temperature of about 250 to 350 F. for about 2 to 4 hours, and then separating unreacted terpene and peroxide decomposition products from the resultant stabilized phosphosulfurized hydrocarbon by distillation.

6. Method according to claim 5 wherein said phosphosulfurized hydrocarbon is a PzSs' treated polyiso butylene.

7. Method according to claim 5 wherein said terpene is u. pinene. T

8. Method according to claim 5 wherein said organic peroxide is tert. butyl hydroperoxide.

9. An odor stabilized phosphosulfurized hydrocarbon product prepared by the method of claim 5.

10. A lubricating oil composition comprising a major proportion of a mineral lubricating oil and about 1.0 to 6.0% by weight, based on the total composition, of an odor stabilized phosphosulfurized product prepared by the method of claim 5.

11. An improved method for reducing the evolution of hydrogen sulfide from a P255 treated polyisobutylene which comprises treating about one part by weight of a P285 treated polyisobutylene with about one part by weight'of a pinene in the presence of about 0.02 part by weight of tert. butyl hydroperoxide at about 250 to 350 F. for about 2 to 4 hours, and removing unreacted a pinene and peroxide decomposition products from the reaction mixture by distillation.

12. An odor stabilized P255 treated polyisobutylene product prepared by the method of claim 11.

13. A lubricating oil composition comprising a major proportion of a mineral lubricating oil and about 1.0 to 6.0% by weight, based on the total composition of an odor stabilized P285 treated polyisobutylene product prepared by the method of claim 11.

References Cited in the file of this patent UNITED STATES PATENTS 2,640,053 Hill May 26, 1953 

1. AN IMPROVED METHOD FOR REDUCING THE EVOLUTION OF HYDROGEN SULFIDE FROM PHOSPHOSULFURIZED HYDROCARBONS WHICH COMPRISES TREATING A PHOSPHOSULFURIZED HYDROCARBON WITH ABOUT 1% TO 200% BY WEIGHT, BASED ON THE PHOSPHOSULFURIZED HYDROCARBON, OF CYCLIC TERPENE IN THE PRESENCE OF ABOUT 0.0001 TO 0.5 MOLE, PER MOLE OF PHOSPHOSULFURIZED HYDROCARBON, OF ORGANIC PEROXIDE HAVING THE FORMUAL 